Container subassembly having a membrane-type closure

ABSTRACT

A container assembly is provided which comprises a composite tubular body having an outwardly rolled top rim which body has an asymmetrically tabbed membrane-type closure sealingly secured to the rolled rim so that the peripheral section of the closure conforms radially and circumferentially to an upwardly facing annular area of the rolled rim. The method of making the container subassembly comprises induction heat sealing a membrane-type closure comprising an electrically conductive sheet to a composite tubular body comprising an electrically conductive liner with electrical insulation means and heat activatable sealant disposed therebetween. The method further comprises biasing the peripheral section of the closure towards the rolled rim with a uniformly distributed force while the induction heat sealing is being effected.

United States Patent 1 Johnson et al.

[451 July 1,1975

[ CONTAINER SUBASSEMBLY HAVING A MEMBRANE-TYPE CLOSURE [75] Inventors: Charles Louis Johnson; Charles Donald Stuard, both of Cincinnati, Ohio [73] Assignee: The Procter & Gamble Company,

Cincinnati, Ohio [22] Filed: July 12, 1974 [21] Appl. No.: 488,101

[52] U.S. Cl 229/43; 229/55; 229/48 T; 220/258; 220/306; 220/359; 215/251 [51] Int. Cl i. 865d 5/64; 865d 43/00 [58] Field of Search 229/55, 43,48 T; 220/256, 257, 258, 308 359, 306; 215/251 [56] References Cited UNITED STATES PATENTS 3,434 65l 3/l969 Stec .v 229/43 3,805,993 4/1974 Enzie et a1. .i 220/308 FOREIGN PATENTS OR APPLlCATlONS 277,860 [/1970 Austria 220/258 Primary Examiner-George T. Hall Attorney, Agent, or FirmThomas J. Slone; John V. Gorman; Richard C. Witte [57] ABSTRACT A container assembly is provided which comprises a composite tubular body having an outwardly rolled top rim which body has an asymmetrically tabbed membrane-type closure sealingly secured to the rolled rim so that the peripheral section of the closure conforms radially and circumferentially to an upwardly facing annular area of the rolled rim. The method of making the container subassembly comprises induction heat sealing a membrane-type closure comprising an electrically conductive sheet to a composite tubular body comprising an electrically conductive liner with electrical insulation means and heat activatable sealant disposed therebetween The method further comprises biasing the peripheral section of the closure towards the rolled rim with a uniformly distributed force while the induction heat scaling is being effected 12 Claims, 19 Drawing Figures WHEN 1 EU JUL 1 I975 SHEET SHEET RF. CONNECTIONS 1 CONTAINER SUBASSEMBLY HAVING A MEMBRANE-TYPE CLOSURE FIELD OF THE INVENTION Providing containers comprising membrane-type closures having integral tabs which may be grasped to enable removal of the closure.

BACKGROUND OF THE INVENTION Various aspects of providing containers having membrane-type closures, and of induction heat sealing membrane-type closures to containers are disclosed in prior art U.S. Pats. of which the following are representative: U.S. Pat. No. 2,937,481 issued May 24, I960 to Jack Palmer; U.S. Pat. No. 3,460,310 issued Aug. 12, 1969 to Edmund Philip Adcock et. al.; U.S. Pat. No. 3,501,045 issued Mar. 17, 1970 to Richard W. Asmus et al.; U.S. Pat. No. 3,734,044 issued May 22, 1973 to Richard W. Asmus et al.; U.S. Pat. No. 3,767,076 issued Oct. 23, 1973 to Leo J. Kennedy; U.S. Pat. No. 3,805,993 issued Apr. 23, 1974 to William H. Enzie et al.; and U.S. Pat. No. 3,808,074 issued Apr. 30, 1974 to John Graham Smith et al. However, the prior art does not disclose solutions to all of the problems associated with providing containers having membrane-type closures in the manner of or degree of the'present in vention.

OBJECTS OF THE INVENTION The nature and substance of the invention will be more readily appreciated after giving consideration to its major aims and purposes. The principal objects of the invention are recited in the ensuing paragraphs in order to provide a better appreciation of its important aspects prior to describing the details of a preferred embodiment in later portions of this description.

A major object of the present invention is providing a container subassembly comprising a composite tubular body and an asymmetrical shape membrane-type closure having an integral pull tab and means for induction heat sealing the closure to the body to effect a hermetic seal therebetween.

Another major object of the present invention is providing a hermetically scalable container subassembly comprising a spirally wound composite tubular body, and an asymmetrical shape membrane-type closure having an integral pull tab.

Still another major object of the present invention is providing the container subassembly described in the preceding paragraph which subassembly comprises means for being induction heat sealed.

Yet still another major object of the present invention is providing the container subassembly described in the preceding paragraph which container further comprises an overcap having heat-deformable means for causing the peripheral section of the closure to conform radially and circumferentially to a rolled rim of the tubular body.

Yet another major object of the present invention is providing a thermoplastic overcap comprising heatdeformable means for causing the peripheral section of a heat-sealable membrane-type closure to conform radially and circumferentially to the rim of a container body when the closure is heat sealed to the rim of the container body.

A still further major object of the present invention is providing a method of induction heat sealing an asymmetrical shape membrane-type closure to the rim of a tubular container body so that the peripheral section of the closure conforms radially and circumferentially to the rim of the tubular body.

SUMMARY OF THE INVENTION The above recited and other objects are achieved in the present invention by providing a container subassembly comprising a membrane-type closure having an integral pull tab, a composite tabular body having a rolled top rim, and heat activatable sealant and electrical insulation disposed intermediate the peripheral section of the closure and the rim of the tubular body. The closure comprises an electrically conductive sheet which is configured to provide a disc portion and an in tegral pull tab. The tubular body comprises a liner of electrically conductive material having a lap seam intermediate overlapped side edge portions. The closure is sealingly secured along a circumferentially extending seam to the rim of the container so that the peripheral section of the disc portion of the closure conforms radially and circumferentially to an upwardly facing annular-shape area of the rolled rim on the tubular body. The container subassembly may further comprise an overcap comprising heat-deformable means for effecting the radial and circumferential conformation of the peripheral section of the closure to the rim of the container body. The method of induction heat sealing an asymmetrical-shape closure comprising an electrically conductive sheet to a tubular body comprising an electrically conductive liner includes the step of biasing the peripheral section of the closure towards the rim of the container body with a uniformly distributed force while adjacent portions of the electrically conductive sheet and the electrically conductive liner are simultaneously heated by induction heating means.

BRIEF DESCRIPTION OF THE DRAWINGS While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter regarded as forming the present invention, it is believed the invention will be better understood from the following description taken in connection with the accompanying drawings in which:

FIG. I is an exploded perspective view of a preferred container subassambly embodying the present invention.

FIG. 2 is a fragmentary perspective view of the container subassembly shown in FIG. 1.

FIG. 3 is an enlarged scale, fragmentary perspective view of the spirally wound and lap seamed liner of the container subassembly shown in FIGS. 1 and 2.

FIG. 4 is a fragmentary sectional view of the liner shown in FIG. 3 taken along line 44 thereof.

FIG. 5 is a fragmentary, radially outwardly looking view of the liner-seam-area of the outwardly rolled rim of the tubular container body shown in FIG. 1.

FIG. 6 is an enlarged scale bottom view of the overcap of the container subassembly shown in FIG. I.

FIG. 7 is an enlarged scale, fragmentary radial sectional view of the overcap shown in FIG. I taken along line 7-7 thereof.

FIG. 8 is an enlarged scale fragmentary circumferential sectional view of the overcap shown in FIGS. 1, 6 and 7 taken along line 88 of FIG. 7.

FIG. 9 is an enlarged scale top view of the membrane-type closure shown in FIG. I prior to folding the integral tab of the closure to the orientation shown in FIGv 1.

FIG. is a fragmentary sectional view of the closure shown in FIG. 9 taken along line 1010 thereof.

FIG. 11 is an enlarged scale radial sectional view of a top edge portion of the container subassembly shown in FIG. 2 taken along line 11-11 thereof which line extends between radially extending ribs depending from the interior surface of the overcap of the subassembly.

FIG. 12 is an enlarged scale circumferential sectional view of the container subassembly shown in FIG. 2 taken along line 12-12 thereof.

FIG. 13 is a reduced scale, end view of a portion of an apparatus for induction heat sealing the closure of the container assembly shown in FIG. 1 to the rim of the tubular body of the container assembly.

FIG. 14 is a reduced scale perspective view of the induction heating electrode of the apparatus shown in FIG. 13.

FIGv 15 is a fragmentary perspective view of an alternate container subassembly embodying the present invention.

FIG. 16 is an enlarged scale top view of an alternate membrane-type closure which may be incorporated in container subassemblies embodying the present invention.

FIG. 17 is an enlarged scale, fragmentary top view of another alternate membrane-type closure which may be incorporated in container subassemblies embodying the present invention.

FIG. 18 is a sectional view of the alternate membrane-type closure shown in FIG. 17 taken along line 18-18 thereof.

FIG. 19 is an enlarged scale, fragmentary top view of yet another alternate membrane-type closure which may be incorporated in container assemblies embodying the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGS 1 and 2, the preferred embodiment of the present invention is a container subassembly 40 which comprises a spirally wound, composite tubular body 41, a membrane-type closure 42 having an integral pull tab 43, and an overcap 44.

Briefly, overcap 44 comprises heat-deformable means such as a multiplicity of circumferentially spaced. radially extending ribs 85 which means are heat-deformed or molded when container subassembly 40 is assembled to cause the peripheral section of closure 42 to conform radially and circumferentially to the rim of tubular body 41 regardless of minor irregularities in the rim of tubular body 41. Further, the container subassembly comprises means for induction heat sealing closure 42 to the rim of tubular body 41 and for causing the heat-deformable means to effect the above described radial and circumferential conformation of the peripheral section of closure 42 to the rim of tubu lar body 41.

Tubular body 41, FIG. I, of the preferred embodiment container assembly 40 is a glue bonded. composite. spirally wound tube construction which tube, after being cut to length, has its top rim 48 rolled outwardly to form a circumferentially extending bead and has its bottom rim 49 flared to enable crimping a bottom closure thereto.

Referring now to FIG. 11, the multi'ply sidewall of tubular body 41, FIG. 1, is shown to comprise three major plies: an innermost ply hereinafter referred to as liner 50, an outermost ply hereinafter referred to as label 51, and a middle ply 52. In the preferred embodiment container assembly 40, FIG. 1, label 51 comprises 55 pound litho paper coated with a moisture barrier which, in turn, is printed and coated with an overprint lacquer; and the middle ply 52 is 19 point kraft paper can board.

Liner 50, FIG. 3, comprises a web of four layer construction as shown in FIG. 4. The innermost layer 53 is a thermoplastic material which forms the radially inwardly facing portion of body 41 when the web is spirally wound and spirally lap seamed as indicated in FIG. 3. The thermoplastic material of the preferred embodiment is a l2 pound coating of Surlyn, DuPont number 1,652 SR, an ionomer resin, although polypropylene and other thermoplastic materials may be used. Surlyn is a registered trademark of the El. DuPont de Nemours Company. The second layer 54 is aluminum foil having a preferred thickness of about thirty-five one-hundred-thousandths of an inch which is adhered to the outermost layer 56 by the third layer 55 of the construction which third layer may be a 7 pound coating of low density polyethylene. The outermost layer 56 may be 25 pound machine finish natural kraft paper.

When the web from which liner 50 is spirally wound into the tubular shape shown in FIG. 3, one side edge portion 60 is doubled back so that the oppositely disposed second side edge portion 61 can be overlapped therewith with the thermoplastic innermost layer 53 of side edge portions 60, 61 in abutting relation. This enables the overlapped side edge portions 60, 61 to be heat sealed together to form a spiral lap seam or body seam 62 having a spiral inner edge 63 and a spiral outer edge 64.

As is shown in FIG. 3, spiral lap seam 62 comprises three thicknesses of the web from which the liner 50 is formed. The two extra thicknesses of liner material in spiral seam 62 precipitate a circumferentially extending hump 65, FIG. 5, in the top rim 48 of tubular body 41, which hump 65 is shown in exaggerated propor tions in FIG. 5 to more clearly disclose that it causes the top rim 48 to have elevational differences around the top opening 66 of tubular body 41 as indicated in FIG. 5 by delta E; (SE).

As will be described more fully hereinafter, elevational differences of rim 48 around top opening 66 which differences are precipitated by lap seams and/or other aspects of making spirally wound composite tu bular bodies such as 41 having outwardly rolled top rims require special attention to hermetically seal a membrane-type closure such as closure 42 to the top rims.

The membrane-type closure 42, FIG. 9,, has an asymmetrical shape, and comprises a disc portion 70 and an integral radially extending tab 43 having its proximal end 71 hingedly secured to the perimeter 72 of disc portion 70. An annular-shape section of disc portion 70 which extends radially inwardly from perimeter 72 is designated peripheral section 73.

As shown in FIG. 10. closure 42 is a three layer construction comprising a top layer 74, a middle layer 75. and a bottom layer 76. In the preferred embodiment closure 42, middle layer 75 is an electrically conductive sheet of type 1 -0 aluminum having a nominal thickness of about 3 mils, top layer 74 is a A pound vinyl washcoat such as Adcoat 41C available from Morton Chemical Company. Chicago. Ill., and the bottom layer is a 1 mil thermoplastic coating of DuPont type XBR 950 ethylene vinyl acetate. The vinyl washcoat is provided as a means for protecting the top surface of the aluminum sheet from oxidation, and the XBR 950 coating is provided on the bottom surface of the aluminum sheet to make the peripheral section 73 of closure 42 peelably heat scalable to an upwardly facing annularshape area of the thermoplastic innermost layer 53 of liner 50 of tubular body 41 which layer 53 is disposed on the top of rim 48 by virtue of rim 48 being rolled outwardly as described hereinbefore.

Together, the portions of the XBR 950 coating and the thermoplastic layer 53 of the liner 50 of tubular body 41 comprise electrical insulation means and heat activatable sealant disposed intermediate the aluminum sheet 75 of closure 42 and the aluminum layer 54 ofliner 50 whereby the peripheral section 73 of closure 42 is susceptible to being induction heat sealed to the top rim 48 of the tubular body 41 to form a hermetic circumferential seam therebetween.

Overcap 44, FIG. 1, of the preferred embodiment is made of thermoplastic material such as low density polyethylene resin type 1400 available from Gulf Oil Chemicals Co., Orange, Texas. Overcap 44, FIGS. 6 and 7, comprises a top panel 80 and an annular skirt 81 depending from the periphery of the top panel 80.

The top panel further comprises an annularshape stacking flange 82 which extends upwardly from the exterior surface 83 of top panel 80. The stacking flange 82 has a planar, annular-shape top surface 84. The stacking flange 82 has a mean diameter substantially equal to the mean diameter of rim 48 of container body 41 so that the stacking flange 82 is superjacent the rim 48 when the overcap 44 is applied to the tubular body 41 as shown in FIGS. 2 and 11.

The top panel 83 of overcap 44 also comprises heat deformable means such as a multiplicity of circumferentially spaced, radially extending ribs 85, FIGS. 6, 7 and 8, which depend from the interior surface of the top panel 80 of overcap 44. The ribs 85 are so disposed that they underlie the stacking flange 82 whereby they radially span the rim 48 of the tubular body 41 when the container subassembly 40 is assembled as shown in FIG. 11. FIG. 7 is a radial sectional view taken between two ribs 85 to show the radially extending profile of a rib 85 and FIG. 8 is a circumferential sectional view taken through the ribs 85 to show their transverse cross-sectional shape. Such heat deformable means as ribs 85 are provided to cause the peripheral section 73 of closure 42 to conform radially and circumferentially to the rim 48 of tubular body 41 by being heatdeformed when the container subassembly 40 is assembled as shown in FIGS. 11 and 12. In the preferred embodiment, ribs 85 have a radial length L, FIG. 7, of about one-quarter of l inch, a width W, FIG. 8, of about six-thousandths, of l inch, are spaced circumfer entially about ten-thousandths of l inch center-tocenter, and have a height H, FIG, 8, of about eightthousandths of 1 inch.

The annular skirt 81 of overcap 44 comprises means for cooperating with overcap engaging means provided on the tubular body 41 adjacent the top rim 48 of the body 41. In the preferred embodiment, the radially inwardly and downwardly extending shoulder 87 comprises the means for cooperating with overcap engaging means on the tubular body 41, and the radially out wardly disposed, radially inwardly and downwardly extending distal portion 88 of the outwardly turned top rim 48 of tubular body 41 comprises such overcap engaging means, all as shown in Fig. 11.

The container subassambly 40, FIGS. 1 and 2 is assembled as shown in the greatly enlarged scale radial sectional view of FIG. 1] taken along line 1111 of FIG. 2, and as shown in the greatly enlarged scale circumferential sectional view of FIG. 12 taken along line l2-12 of FIG. 2. Briefly, the preferred method of so assembling container subassembly 40 comprises biasing the overcap 44 towards the rim 48 of the tubular body 41 while adjacent portions of the peripheral section 73 of closure 42, rim 48, and ribs are simultaneously heated by induction heating means to a sufficiently high temperature to heat-deform the ribs 85 to cause them to evenly distribute the biasing force across the closure-rim interface to cause the peripheral section 73 of closure 42 to conform radially. FIG. 11, and circumferentially, FIG. 12, to rim 48 as shown, and to be hermetically sealed thereto along a circumferentially extending seam 89. By virtue of heatdeforming ribs 85 as shown in FIGS. 11 and 12, the peripheral section 73 of closure 42 can be made to so conform to rim 48 regardless of elevational differences caused by the seam 62 of the liner 50 (i.e.: hump 65, FIG. 5), or the presence of tab 43, FIG. 12.

Preferably, the biasing force is applied from a planar surface of a biasing device such as spring 96 incorporated in an induction heating device 97 to the planar surface 84 of overcap 44 as shown in FIG. 13 while carriage 98 is drawn along cylindrical guides 99, 100 by a chain 101 attached to the carriage 98 is drawn around a driven sprocket 102. By virtue of shafts 103, 104 being freely rotatable in the upstanding ends 105, 106 respectively of carriage 98, and by virtue of a pinion gear 107 being drivingly secured to shaft 103 and drivingly engaged with a stationary rack gear 108, a loosely assembled container subassembly 40 can be supported between cups 109, 110, and rolled past the noncontacting linear sections 111, 112 of induction heating electrode 113, FIG. 14, as the carriage 98 is moved. As shown in FIG. 13, linear section 111 of electrode 113 is disposed substantially (but not touching) tubular body 41 subjacent the top rim of the body, and the linear section 112 of electrode 113 overlies the overcap 44 and closure 42 radially inwardly from the rim of the body and extends chordally with respect to the rim. Thus, by energizing electrode 113 by a suitable RF source (not shown) adjacent portions of the electrically conductive sheet 75 of closure 42 and the electrically conductive layer 54 of liner 50 can be simultaneously induction heated wherby adjacent portions of the ribs 85 of the overcap 44, the thermoplastic coating 76 of closure 42, and the thermoplastic innermost layer 53 of liner 50 are simultaneously conductively heated. When thus heated to a sufficiently high temperature, the biasing force will precipitate the above described radial and circumferential conformation, and the hermetic circumferential seam 89 will be formed.

Ribs 85a, FIG. 12 illustrate the heat-deformation of the ribs which causes the biasing force to be equally distributed around the peripheral section 73 of closure 43 during the induction sealing operation described above. Were the tabs 85a disposed superjacent the tab 43 not so deformed, the biasing force would be concentrated in the tab area. This concentration of bias might precipitate damage to the underlying portion of rim 48 and/or reduce the bias around the remainder of the rim to a value too low to effect good sealing.

The Model 5,000 R.F.C. High Frequency Generator which is available from the Radio Frequency Company, 44-46 Park Street, Medfield, Mass. is such a suitable RF source referred to above.

During the assembly and sealing of the preferred container subassembly described hereinabove which subassembly 40 comprises a tubular body 41 having an inner diameter of about 2% inches, the RFC. Generator was operated at a plate current of about l 3/10 amperes, a spring biasing force of about 30 pounds was applied, and the carriage was drawn past the linear sections 111, 112 of electrode 113 at about 2 feet per second. The linear sections 111, 112 of electrode 113 were approximately 12 inches long.

During such induction heat sealing as described above, and with the tab 43 of the closure 42 oriented away from the seam 62 in liner S of body 41 as shown in FIGS. 1 and 2, the maximum temperature achieved under the proximal end 71 of tab 43 was in the range of from about 230 to about 239 Fahrenheit while the maximum temperature achieved around the rest of the rim 48 was in the range of from about 270 to about 279 Fahrenheit.

The tensile strength of the peelable bond achieved between XBR 950 and Surlyn (registered trademark of the DuPont Company) or polypropylene is directly related to the temperature achieved during the heat sealing operation. Thus, because the maximum temperatures achieved under the proximal end 71 of tab 43 and above the body seam 62 in the rolled rim of body 41 were lower than in the remainder of the circumferential seam 89, it follows that the tensile strength of the circumferential seam 89 is smaller under the tab 43 and above the body seam 62 than in the remainder of the circumferential seam 89.

However, in similar subassemblies wherein either the electrically conductive sheet is omitted from the closure or the electrically conductive layer is omitted from the tubular body, the tensile strength of the circumfer ential seam is, as compared to the preferred embodiment container subassembly, inferentially, much lower as witnessed by the following examples,

When a container subassembly like the preferred embodiment but for omitting the electrically conductive sheet from the closure was subjected to the sealing conditions described hereinabove, the maximum temperature achieved intermediate the peripheral section of the closure and the rim of the tubular body was in the range of from about I to about l29 Fahrenheit; less than one half that achieved in the preferred embodiment.

Similarly, when a container subassembly like the preferred embodiment but for omitting the electrically conductive layer in the rim of the tubular body was subjected to the same sealing conditions, the maximum temperature achieved under the proximal end of the tab was in the range of from about I H) to about 1 19 Fahrenheit and the maximum temperature in the cir cumferential seam area spaced away from the tab and the body seam was in the range of from about 130 to about 139 Fahrenheit, also less than about one half that achieved in the preferred embodiment.

From the foregoing, it is clear that both the electri cally conductive sheets in the closure 42 and the electrically conductive layer in the liner of tubular body 41 are required to enable inductively sealing those members of the subassembly together in the manner described hereinbefore. Also, by virtue of making the electrically conductive sheet and layer of aluminum, the resulting container subassembly is subject to being hermetically sealed by crimping a suitable hermetic closure to the bottom end of the tubular body. However, the electrically conductive members must be electrically insulated from each other to prevent arcing during induction heating.

Referring now to FIG. 15, an alternate container subassembly 400 is shown which comprises the same tubular body 41, closure 42, and overcap 44 as the preferred container subassembly 40, FIGS, 1 and 2. ln deed, the subassemblies 40 and 40a are identical but for the fact that closure 42 of subassembly 40, FIG. 2, is oriented with respect to the rim of the tubular body 41 so that the proximal end of the tab 43 is not disposed superjacent the portion of the lapped body seam 62 disposed in the rim of the tabular body in the preferred assembly 40, whereas the closure 42 of subassembly 40a, FIG. 15, is oriented with respect to the rim of the tubular body 41 so that the proximal end of the tab 43 is dis posed superjacent the portion of the lapped body seam 62 of the tabular body 41 disposed in the rim 48 of the tabular body in the alternate container subassembly 40a.

As will become apparent from the following example, the circumferential seam 89, FIG. 11, of preferred embodiment container subassembly 40, FIGS. 1 and 2, has greater structural integrity than the circumferential seam in the alternate subassembly 40a, FIG. 15. However, because the tensile strength of the circumferential seam subjacent tab 43 of subassembly 40a is less than in subassembly 40, the initial pull required to begin peeling closure 42 from the tubular body 41 is commensurately less. Therefore, a container comprising subassembly 40a is easier to open than a container comprising subassembly 40 and for that reason more desirable for some container applications than a container comprising a subassembly 40.

The reduced initial pull required to peel a closure from an alternate container subassembly 40a, FIGv 15, is inferred from the fact that when such an assembly is subjected to the same sealing conditions described in conjunction with the preferred embodiment container subassembly, the maximum temperature achieved subjacent the proximal end of the tab of the closure is in the range of from about 170 to about I 79 Fahrenheit, while the maximum temperature achieved in the remaining portion of the circumferential seam is in the range of from about 270 to about 279 Fahrenheit; over twice the differential measured in the preferred container assembly 40, FIGS. 1 and 2, as set forth hereinabove. Indeed, the pull required on the tab of the closure to initiate peeling the closure from the preferred embodiment 40 is greater than two times that required for the alternate container subassembly 40a.

Referring now to FIG. 16, an alternate closure embodiment 42a is shown which has an aperture disposed in the proximal end 71a of tab 430 adjacent the disc portion 700 of the closure. Insuch a closure having a 3/16 inch diameter aperture in a onehalf-inch wide tab, the temperature differential experienced between the area under the tab and the other portions of the circumferential seam during induction heat sealing was reduced by about 25 percent from the differential experienced in the preferred embodiment described hereinbefore. Thus, container subassemblies comprising the alternate closure 420 would have greater structural integrity than the preferred embodiment. It is believed that the benefit of increased structural integrity available through using alternate closures 420 must be balanced against the need therefore and the cost thereof. Other alternate closure embodiments 42b, and 42: are shown in FIGS. 17 and 19 respectively. However, the elongate apertures 121 disposed in the proximal end of the tab are formed by making C-shape cuts to form flaps 122, FIG. 18, and by folding the flaps 122 as shown in FIG. 18. Such a method of providing apertures obviates scrap removal which would be required in the manufacture of alternate closures 42a, FIG. 16.

While particular embodiments of the present invention have been illustrated and described, it will be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention and it is intended to cover, in the appended claims. all such changes and modifications that are within the scope of this invention. I

What is claimed is: l. A container subassembly comprising a membranetype closure, a composite tubular body having an outwardly rolled top rim, and heat activatable sealant and electrical insulation means disposed intermediate said closure and said rim of said body,

said closure comprising an electrically conductive sheet which is configured to provide a disc portion and an integral radially extending tab, said tab being folded so that it extends radially inwardly from the perimeter of said disc portion and is disposed superjacent the top surface of said disc portion, said body comprising a liner formed form a web of electrically conductive material which is spindled into a tabular shape so that oppositely disposed side edge portions are sealingly secured together in overlapped relation to form a body seam, and

said closure being sealingly secured by said heat activatable sealant to said rim along a circumferentially extending seam with said electrical insulation means disposed therebetween so that the peripheral section of said disc portion conforms radially and circumferentially to an upwardly facing annular-shape area of said rim.

2. The container subassembly of claim 1 wherein said electrical insulation means compises a thermoplastic coating on the bottom surface of said sheet, and

a layer of thermoplastic material adhered to the radially inwardly facing surface of said liner, said thermoplastic material being heat scalable to said thermoplastic coating,

whereby said closure is sealingly secured to said rim by heat sealing the peripheral section of said thermoplastic coating on said closure to the portion of said thermoplastic material of said liner which is disposed on the upwardly facing area of said rim by virtue of said rim being outwardly rolled.

3. The container subassembly of claim 2 wherein said thermoplastic coating and said thermoplastic layer are selected from the group comprising ethylene vinyl acetates, Surlyns which are ionomer resins, and polypropylene whereby said closure is rendered peelably heat scalable to said rim of said tubular body and said seam is substantially hermetically sealed.

4. The container subassembly of claim 3 wherein said ethylene vinyl acetates comprise DuPonts XBR 950, and said Surlyns comprise Surlyn number 1652 SR.

5. The container subassembly of claim 4 wherein said thermoplastic coating is DuPonts XBR 950, and said thermoplastic layer is DuPonts Surlyn number l652 SR.

6. The container subassembly of claim 2 wherein said liner is spirally wound and said body seam is spiralshape whereby said body seam intersects said rim and precipitates a circumferentially extending body-seam hump on said rim due to said overlapped side edge portions.

7. The container subassembly of claim 6 wherein said closure is oriented with respect to said rim that the distal end of said tab is circumferentially spaced from said body-seam hump on said rim.

8. The container subassembly of claim 6 wherein said closure is oriented with respect to said rim so that the distal end of said tab is disposed superjacent said bodyseam hump.

9. The container subassembly ofclaim 1 further comprising an overcap comprising a top panel and an annular skirt depending from the periphery of said top panel, said top panel comprising heat-deformable means for causing said radial and circumferential con formation of said peripheral section of said closure to said rim area when said overcap is biased towards said rim by a biasing device which presents a planar surface to the exterior of said top panel while said heatdeformable means is heated to a sufficiently high tem' perature to enable heat-deformation thereof.

10. The container subassembly of claim 9 wherein said heat-deformable means comprises a multiplicity of circumferentially spaced, radially extending, depending ribs of thennoplactic material disposed adjacent the perimeter of said top panel so that said ribs overlie said rim.

1]. The container subassembly of claim 9 wherein an aperture is provided in said tab adjacent said disc to improve the capability of induction heat sealing said clo sure to said annular area of said rim.

12. A container subassembly comprising a body having a top rim, a membrane'type closure, an overcap, and means for heat sealing a peripheral section of said closure to said rim along a circumferentially extending seam when heated to a predetermined temperature, said overcap comprising heat-deformable means for uniformly distributing a biasing force from a planar surface to uniformly bias the peripheral section of said closure against said rim when said heat-deformable means is heated to said predetermined temperature whereby the peripheral section of said closure is caused to conform radially and circumferentially to said rim and to be sealingly secured thereto upon applying said biasing force while heating said section, rim, and heatdeformable means to said predetermined temperature, and then cooling said section, rim, and heatdeformable means to a sufficiently low temperature to set said circumferential seam while maintaining said hi asing force. 

1. A container subassembly comprising a membrane-type closure, a composite tubular body having an outwardly rolled top rim, and heat activatable sealant and electrical insulation means disposed intermediate said closure and said rim of said body, said closure comprising an electrically conductive sheet which is configured to provide a disc portion and an integral radially extending tab, said tab being folded so that it extends radially inwardly from the perimeter of said disc portion and is disposed superjacent the top surface of said disc portion, said body comprising a liner formed form a web of electrically conductive material which is spindled into a tabular shape so that oppositely disposed side edge portions are sealingly secured together in overlapped relation to form a body seam, and said closure being sealingly secured by said heat activatable sealant to said rim along a circumferentially extending seam with said electrical insulation means disposed therebetween so that the peripheral section of said disc portion conforms radially and circumferentially to an upwardly facing annularshape area of said rim.
 2. The container subassembly of claim 1 wherein said electrical insulation means compises a thermoplastic coating on the bottom surface of said sheet, and a layer of thermoplastic material adhered to the radially inwardly facing surface of said liner, said thermoplastic material being heat sealable to said thermoplastic coating, whereby said closure is sealingly secured to said rim by heat sealing the peripheral section of said thermoplastic coating on said closure to the portion of said thermoplastic material of said liner which is disposed on the upwardly facing arEa of said rim by virtue of said rim being outwardly rolled.
 3. The container subassembly of claim 2 wherein said thermoplastic coating and said thermoplastic layer are selected from the group comprising ethylene vinyl acetates, Surlyns which are ionomer resins, and polypropylene whereby said closure is rendered peelably heat sealable to said rim of said tubular body and said seam is substantially hermetically sealed.
 4. The container subassembly of claim 3 wherein said ethylene vinyl acetates comprise DuPont''s XBR 950, and said Surlyns comprise Surlyn number 1652 SR.
 5. The container subassembly of claim 4 wherein said thermoplastic coating is DuPont''s XBR 950, and said thermoplastic layer is DuPont''s Surlyn number 1652 SR.
 6. The container subassembly of claim 2 wherein said liner is spirally wound and said body seam is spiral-shape whereby said body seam intersects said rim and precipitates a circumferentially extending body-seam hump on said rim due to said overlapped side edge portions.
 7. The container subassembly of claim 6 wherein said closure is oriented with respect to said rim that the distal end of said tab is circumferentially spaced from said body-seam hump on said rim.
 8. The container subassembly of claim 6 wherein said closure is oriented with respect to said rim so that the distal end of said tab is disposed superjacent said body-seam hump.
 9. The container subassembly of claim 1 further comprising an overcap comprising a top panel and an annular skirt depending from the periphery of said top panel, said top panel comprising heat-deformable means for causing said radial and circumferential conformation of said peripheral section of said closure to said rim area when said overcap is biased towards said rim by a biasing device which presents a planar surface to the exterior of said top panel while said heat-deformable means is heated to a sufficiently high temperature to enable heat-deformation thereof.
 10. The container subassembly of claim 9 wherein said heat-deformable means comprises a multiplicity of circumferentially spaced, radially extending, depending ribs of thermoplactic material disposed adjacent the perimeter of said top panel so that said ribs overlie said rim.
 11. The container subassembly of claim 9 wherein an aperture is provided in said tab adjacent said disc to improve the capability of induction heat sealing said closure to said annular area of said rim.
 12. A container subassembly comprising a body having a top rim, a membrane-type closure, an overcap, and means for heat sealing a peripheral section of said closure to said rim along a circumferentially extending seam when heated to a predetermined temperature, said overcap comprising heat-deformable means for uniformly distributing a biasing force from a planar surface to uniformly bias the peripheral section of said closure against said rim when said heat-deformable means is heated to said predetermined temperature whereby the peripheral section of said closure is caused to conform radially and circumferentially to said rim and to be sealingly secured thereto upon applying said biasing force while heating said section, rim, and heat-deformable means to said predetermined temperature, and then cooling said section, rim, and heat-deformable means to a sufficiently low temperature to set said circumferential seam while maintaining said biasing force. 